Tremendous excitement has been generated by the use of botulinum toxin for the treatment of various types of urethral and bladder dysfunction over the past several years. Botulinum toxin is the most lethal naturally occurring toxin known to mankind. Why, then, would an urologist want to use this agent to poison the bladder or urethral sphincter? In this review article we will examine the mechanisms underlying the effects of botulinum toxin treatment. We will discuss the current use of this agent within the urologic community and will provide perspectives on future targets of botulinum toxin.